Device for internal calipering



Sept. 16, 1958 L. PERAS 2,851,783

DEVICE FOR INTERNAL CALIPERING Filed Nov. 2. 1954 2 Sheets-Sheet 1 INVENTOR. LUCIEN PERAS ATTORNEY Sept. 16, 1958 PERAs DEVICE FOR INTERNAL CALIPERING 2 She ets-Sheet 2 Filed Nov. 2. 1954 DEVICE FORINTERNAL CALIPERING l. "Lucien c 'Peras,':?Billancourt,-i: "France; assignor to: "-Regie Nationale--.des UsinesnRenault, BillancourhIFi-ance, a

French works Application November 2,*1954,Serial No. 466,399

. I Claims priority, wapplicationFranee November 27,1953 1 Claims. '(Cl.' 33 -178) Series'tru'eing ot"internallyirevolving surfacescan only 'be' effected: with"great'precision on trueing machines equipped with" devices allowing the operator: constant control ofthe increase in. internal diameter of the piece to be truedgorwith adevice which automatically stops the trueingcycle when the "bore of the'piece has reached "the desired'reading.

' Thedevice'shitherto proposed for this'purpose generally comprise alever;the'pivot1point"of which is attached to ""the frameof "the;'n1a'c'hi'ne',and which carries a diamond feelermaintained in "contact with the bore to be tru'ed. The variations in theradiusofith'e latter react on the move- ":ments "of the"l'ever,"isaid movements, amplified by .an appropriate device, controlling for example .the cycle of the machine. These known devices have certain disadvantages, especially that of a relatively low degree of precision, due to thetact'that'the comparative"measurements are efiected .withrreferencerto :theframeof the machine. Thus areadded all the sources. oferror. arising from play -.in themachinqdifierence's in thepositions of successive tipieces .in'..tl1e mandrel, etc.

The invention i'elates to a device 'for internal calipering for determining'.the.diameter of aibore. According to the invention zmeasurement is efiectedwith thehelp of two --.diametrically opposed contact' feelers. protruding-tram theexternal surfaceof a calipering barrel. The latter is split in such a'lwaysasno-icomprise.two elements or portions, eachcarryingionecontact. feeler, and .connected to "one another by intermediate members of thin section, giving the barrel a certain elasticity in radial expansion and compression.

This deformabili'ty of the barrel allows it to be introduced into a bore having a diameter slightly smaller than the distance normally separating the contact surfaces of thefeelers on the barrel in the non-deformed state, and an amplifying device indicates the difference between this diameter and the standard distance. When the device is used on a trueing machine, the development of the expansion of the calipering barrel during the finishing movements of the grindstone controls, for example, the working cycle of the machine.

Such a device ensures great precision of calipering, since measurement of the variations in diameter of the bore, which is more favorable than that of the variations in the radius, is virtually uninfluenced by vibration, the

entire device being guided by the bore to be measured.

Two embodiments of devices according to the invention are described below by way of non-limitative examples and with reference to the attached drawing, wherein: Fig. 1 is a perspective diagrammatic view of the operation of a calipering gauge;

Fig. 2 is a comparable view of a different embodiment. In Fig. 1, the workpiece or body to be trued is designated by 1, and is being rotated in the direction of the arrow 2 by means of the mandrel (not shown) of a machine for tracing internally revolving surfaces. The grinding spindle 3, shown in the withdrawn position, causes the grindstone 4 to turn in the direction of the 2,851,783 Patented Sept.- 16,v 1958 -2 arrow 5. The grinding spindle 3 also effects. duringihe working cycle longitudinal reciprocal .movementsain accordance with the arrow 6 and a transverse movement in accordance with the arrow 7.

The calipering gauge comprises a support Siof triangular form, pivoting about a'bar 9,"part. of thistsupportbeing formed as a jaw'ltl. The bearing.plate12.ofthemalipering barrel13 is attachedto this jaw. bythe screws.:.11. This barrel is split-at 14, and, for a. greater width, at 15. Two thin sections '16. and 17. are provided attheextren ity of the barrel." The split 14 extends.asfarzaszthebearing plate '12 andthe flange 12' of. this L-bearingplate is..connected to the member .attachedtothesupport v8.only;by

15 meanslof a member 18 of thinsection. Two feelers.19

and 20, of diamond for. example, are fitted. inthe. walls ofthe two .portions of.1 3a.and 13b of the.barrel,..the contact surfaces of said feelers facing outwards.

. Since .the flange 12 isnot-attached to .theasupport 8, it can easilybe seen that the portion of therbarrelcarrying the feeler 19 canbend resiliently about anaxis 21, perpendicular to the general axis of .the barrel, and ahoutian axisparallel to the axis .ofthe barreland passing-through .the narrow section 18.

The flangelZ' also carries azlever 22 :actinginconjunction with a detecting device 23, attached.to the-support 8, and connected by the conduit 24.to amamplifysingdevicelnot shown), ofknownrconstruction, a.pneumatic amplifier. for example.

apiece. or body Zlhaving beentrued up. to within approxi- The devicetunctions as follows: The bore of thework- .zmately 0.01 mm. of :the reading .to:..be. .obtained,..the .grinding spindle 3 withdraws. in a conventionalworking cycle for. the-purpose of :lining upithe-grindstone -which 1 thus leavesrthe borex During this period when thegrindstone isbeing lined up,.the-calipering gauge. is placedrin position between the workpiece or body lz and thegrind- .stone 4 by pivoting .of the support 8 abouttthe bar 9. The

.- wholezthenroccupies the position shown inwFig. l.

Thedistance betweenthe contact surfaces-.ofthe-teelers .:19.and.2t3'being adjustedto awreadingiof a--.fewmicrons the portion provided with a feeler 19 bending resiliently about the axis 21 and the thin section 18. The grinding spindle 3 then advances towards the workpiece 1, the grindstone 4 enters the bore already containing the barrel, and effects therein, due to the existence of the wide split 15 in the barrel, the finishing movements, the spindle 3 simultaneously moving in the direction of the arrow 7.

The diameter of the bore increasing, and the feelers 19 and 20 remaining in [contact with the wall of the workpiece, the expansion of the calipering barrel leads to a displacement of the lever 22, to which the detector 23 is sensitive. The operator of the machine can thus follow, by means of the amplifying device, the development of the diameter of the bore, and the amplifier can, for example, automatically control the stopping of the trueing cycle when the final reading is reached.

Fig. 2 shows a different embodiment of the internal calipering gauge according to the invention. The support 8 pivots about the bar 9 and carries the bearing plate 12 of the barrel 25, this latter being completely open at its two extremities and comprising two portions carrying the contact feelers 26 and 27, respectively. The portion of the barrel carrying the feeler 26 and comprising the flange 12' of the bearing plate can bend resiliently about the axis 2829 passing through the grooves 30 and 31 forming thin sections allowing the calipering barrel to be compressed and to expand. The flange 12' of the bearing plate carries the adjustable feeler 32, the detector 23 being attached, via the bearing plate 12, to the support 8 and 3 connected by the conduit 24 to the amplifying device (not shown).

The devices described only represent particular embodiments, and it is quite evident that modifications may be made thereto, more particularly to adapt them to the types of pieces to be calipered, without going outside the scope of the invention.

I claim:

1. A device for calipering an internal cylindrical surface comprising, in combination, a support and a slotted barrel extending from one side thereof, said support being pivoted so that said barrel is adapted to be introduced into a workpiece having said internal cylindrical surface, said barrel having a central bore, said barrel comprising a first portion rigid with said support and a second portion free from connection with said support, and articulating means interconnecting the second portion with the rigid first portion to permit said portions to bend relatively to each other and a feeler carried by each portion at diametrically-opposite sides of said barrel for engagement with the cylindrical surface.

2. A device for calipering an internal cylindrical surface comprising, in combination, a support and a slotted barrel extending from one side thereof, said support being pivoted so that barrel is adapted to be introduced into a workpiece having said internal cylindrical surface, said barrel having a central bore, said barrel comprising a first portion rigid with said support and a second portion free from connection with said support, and articulating means interconnecting the second portion with the rigid first portion to permit said portions to bend relatively to each other, a feeler carried by each portion at diametricallyopposite sides of said barrel for engagement with the cylindrical surface, and detector means sensitive to the radial compression and expansion of the barrel as said portions bend about said articulation means in response to the contact of said feelers with the cylindrical surface.

3. A device for calipering an internal cylindrical surface comprising, in combination, a support and a slotted barrel extending from one side thereof, said support being pivoted so that said barrel is adapted to be introduced into a workpiece having said internal cylindrical surface, said barrel having a central bore, said barrel comprising a first portion rigid with said support and a second portion free from connection with said support, and articulating means along two mutually perpendicular axes interconnecting the second portion with the rigid first portion to permit said portions to bend relatively to each other, and a feeler carried by each portion at diametrically-opposite sides of said barrel for engagement with the cylindrical surface.

4. A device for calipering an internal cylindrical surface comprising, in combination, a support and a slotted barrel extending from one side thereof, said support being pivoted so that said barrel is adapted to be introduced into a workpiece having said internal cylindrical surface, said barrel having a central bore, said barrel being formed from a single integral body comprising a first portion rigid with said support and a second portion free from connection with said support, and articulating means interconnecting the second portion with the rigid first portion to permit said portions to bend relatively to each other, and a feeler carried by each portion at diametrically-opposite sides of said barrel for engagement with the cylindrical surface.

5. A device for calipering an internal cylindrical surface comprising, in combination, a support and a slotted barrel extending from one side thereof, said support being pivoted so that said barrel is adapted to be introduced into a workpiece having-said internal cylindrical surface, said barrel having a central bore, said barrel being formed from a single integral body comprising a first portion rigid with said support, and articulating means interconnecting the sccond portion with the rigid first portion to permit said portions to bend relatively to each other, said articulating means being defined by portions of reduced thickness in said barrel body between said portions, and a feeler carried by each portion at diametrically-opposite sides of said barrel for engagement with the cylindrical surface.

References Cited in the file of this patent UNITED STATES PATENTS 2,566,970 Swensson Sept. 4, 1951 2,590,170 Gates Mar. 25, 1952 2,595,917 Bath et a1. May 6, 1952 FOREIGN PATENTS 904,443 France Nov. 6, 1945 993,109 France Oct. 26, 1951 OTHER REFERENCES Publication, American Machinist, May 22, 1947, page 162. 

